WARNING: The following article contains spoilers for RWBY/Justice League #3 by Marguerite Bennett, Emanuela Lupacchino, Wade von Grawbadger, Hi-Fi and Gabriela Downie, on sale now from DC.
From the moment DC announced its Rooster Teeth crossover comic RWBY/Justice League, we knew the digital-first series would feature RWBY's own versions of Superman, Batman, Wonder Woman, Aquaman, the Flash, Cyborg and Jessica Cruz/Green Lantern. However, issue #3 (which has just gone on sale in print) introduces a previously-unadvertised DC hero to the World of Remnant: the speedster known as Jesse Quick.
Created by Len Strazewski and Mike Parobeck, Jesse Chambers originally debuted in 1992's Justice Society of America #1. The daughter of Golden-Age DC heroes Johnny Quick and Liberty Belle, Jesse used her father's formula to tap into the Speed Force, taking on the alter ego of Jesse Quick. An associate of founding Titans member Wally West/the Flash, Jesse briefly joined the team, though lost her speed powers following a battle with Zoom.
Jesse later obtained super strength and carried on her mother's legacy, joining the revived JSA as the new Liberty Belle. The second-generation hero eventually regained her super speed shortly after Barry Allen/the Flash returned from the dead, and reclaimed the mantle of Jesse Quick just before DC's New 52 relaunch. Meanwhile, Jesse Wells, an alternate, live-action version of Jesse Quick played by Violett Beane, was introduced to the Arrowverse in 2015.
RWBY/Justice League #3 opens on the duo of Ruby Rose and Bruce Wayne as they investigate "the Flash," a mysterious, red and gold-clad speedster vigilante reportedly operating around Vale's Faunus District. Ruby and Bruce -- the latter of whom is himself a bat faunus -- examine the crowd for potential suspects, specifically looking for faunus whose animal traits lend themselves to super speed.
The amateur detectives think they've found they're speedster when they spot a fox faunus decked out in red and gold gear. Ruby -- a speedster in her own right -- gives chase, following the self-described "wily" fox through the streets and up rooftops. The chase comes to a halt when it is interrupted by the real Flash, who introduces himself as Barry Allen. Ruby quickly realizes that Barry is the last thing her and Bruce ever expected him to be: a tortoise faunus.
Barry soon introduces his partner in crime as Jesse. As it turns out, Jesse is the one who vets strangers who come looking for Barry. Their similar penchant for red gear is an added bonus, as it helps throw people off. Basically, the idea is that most people searching for the mysterious red and gold speedster will find Jesse, realize she's fast but not that fast, then drop the issue.
Due to a recent string of kidnappings committed by brainwashed hunters-in-training with bizarre glowing eyes -- including Ruby's close friends Jaune Arc and Pyrrha Nikos -- Barry and Jesse are, needless to say, a bit wary of Ruby and Bruce. Nevertheless, they invite the two back to their home to discuss the matter further, at which point it is revealed that Barry's mother, Nora Allen, is actually alive and well in the RWBY-verse.
Ruby and Bruce share their findings with Barry and Jesse, the key point being that someone (or something) in Remnant is controlling the minds of not only humans and animals, but also deadly Creatures of Grimm. The potentially disastrous implications of this seem to be enough to convince Barry to join their quest and get to the bottom of what's really going on.